Fix: Migrate resourceType structured data to linked data

coscine/issues#2083

src/SQL2Linked/Implementations/ResourceTypeStructuralData.cs

@@ -6,10 +6,44 @@ namespace SQL2Linked.Implementations
 {
     public class ResourceTypeStructuralData : StructuralData<ResourceType, ResourceTypeModel>
     {
+        public readonly string ResourceTypeUrlPrefix = "https://purl.org/coscine/resourcetype";
+        public readonly Uri RdfType = new("http://www.w3.org/1999/02/22-rdf-syntax-ns#type");
+        public readonly Uri DcatDataService = new ("http://www.w3.org/ns/dcat#DataService");
+
         public override IEnumerable<IGraph> ConvertToLinkedData(IEnumerable<ResourceType> entries)
         {
-            // ToDo: Implement
-            throw new NotImplementedException();
+       
+            var graphs = new List<IGraph>();
+
+            foreach (var entry in entries)
+            {
+                var resourceTypeGraphName = $"{ResourceTypeUrlPrefix}/{entry.Id}";
+                var graph = RdfStoreConnector.GetGraph(resourceTypeGraphName);
+
+                // check if a triple with a dcat:DataService already exists in the resourcetype graph
+                var getTriples = graph.GetTriplesWithObject(DcatDataService);
+
+                if (!getTriples.Any())
+                {
+                    graph.Assert(
+                        new Triple(
+                            graph.CreateBlankNode(),
+                            graph.CreateUriNode(RdfType),
+                            graph.CreateUriNode(DcatDataService)
+                        )
+                    );
+
+                    graphs.Add(graph);
+
+                    Console.WriteLine($"Will migrate resource type '{entry.DisplayName}' with id '{entry.Id}'.");
+                }
+                else
+                {
+                    Console.WriteLine($"Will NOT migrate resource type '{entry.DisplayName}' with id '{entry.Id}'.");
+                }
+            }
+            return graphs;
         }
     }
+    
 }
\ No newline at end of file

[Benedikt Heinrichs]

Don't use a BlankNode here, since https://purl.org/coscine/resourcetype/{resourceTypeId} was required.